A test for comparing the means of two samples, or the mean of one sample (or even parameter estimates) with a specified value; also known as the "Student t-test" after the pseudonym of its inventor.

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2answers
30 views

What test to compare three groups with data before and after an intervention?

I am writing a proposal for a study. I have 3 groups: Group A- receiving specialized intervention technique Group B- receiving regular intervention Group C- control/receiving no intervention I ...
2
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1answer
37 views

Why would I want to bootstrap when computing an independent sample t-test? (how to justify, interpret, and report a bootstrapped t-test)

Let's say I have two conditions, and my sample size for the two conditions is extremely low. Let's say I only have 14 observations in the first condition and 11 in the other. I want to use the t-test ...
3
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1answer
36 views

p-value correction for multiple t-tests?

My dataset consists of $n$ genes, each of them described by a vector of expression values, $5$ for "healthy" individuals, and $5$ for "unhealthy" individuals. I am going to run $n$ t-tests (one for ...
3
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0answers
10 views

chi-squared test vs fisher's test vs … => highly unbalanced length frequency data

I would like to statistically verify if two distributions are identical. Basically, the first distribution is a length frequency distribution from a large population ("population"). The second is the ...
2
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3answers
118 views

Bootstrap two-sample t test

I'd like to bootstrap a two sample t-test. My DV is some psychological variable. I have two groups (women and men), unequal sizes and I do not assume equal variances. I'm not sure if my code or/and my ...
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1answer
12 views

Is it valid to run unpaired t-tests with large N in one condition and small N in the other?

Basically, I have collected sets of data from two demographic groups. One of my demographic groups (say, Male) I have lots and lots of data (N=182). In my other demographic group (say, Female) I have ...
4
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4answers
102 views

Paired t-test when each data point was repeatedly measured different number of times?

I have an existing data set that comes from the same group of people before and after they received a treatment. The data set comes from when participants tested their blood sugar values over a 30 ...
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1answer
34 views

Is this a right way to use paired t-test

Problem Description I want to enhance a photo and I have 3 software to do that, out of which 2 are my own. I show users 2 photos and ask them to choose a better one. Now, I compare software 1 vs. 2, ...
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0answers
20 views

Appropriate Test of Significance for Eye Tracking Data

Hello my clever friends, I conducted an eye-tracking study and now I'm in statistical hot water. Given the characteristics of the data, I am not sure which test of significance to apply to answer the ...
3
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7answers
229 views

How to judge if 5 point Likert scale data are normally distributed?

I have read that the t-test is used when the population is normally distributed. How can I determine if my data are normal given that I am using 5-point Likert scale with a sample size of 100? What ...
0
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1answer
12 views

Mean comparison of two categorical variables

I'd like to compare people's perception of safety at a certain location [which is a categorical variable on a scale of 1-10, with 1=feel very unsafe & 10=feel very safe] before and after being ...
2
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1answer
39 views

How can I test and quantify the change in distribution over multiple years?

I have a data set of energy usage values taken every half hour for a year, for four years. How can I test for, and quantify, an improvement (i.e. decrease) in energy usage, per-year? I have initially ...
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0answers
19 views

What analysis should I run?

For an RCT, I want to test scores on BES(Binge Eating Scale) and BMI over time for two different groups(experimental and control group)to register whether treatment had an effect on reducing symptoms ...
0
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1answer
25 views

Compare two distributions of large sizes and unequal variances where one distribution is heavily skewed

My data is from cells that are treated under two different conditions and then their response to the condition is measured by one output variable. The cell populations in the two conditions are quite ...
0
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0answers
27 views

T-test or ANOVA

I have 4 groups. I would like to compare the effect of 3 different treatments relating to drug treatment of a sample individually against a single control sample. Control (no drug) Treatment A (low ...
0
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2answers
58 views

How do I obtain a t distribution?

I performed an independent groups t-test and got a t value of 4.48. Each group is of 26 and I used a criterion of 0.05 (just because...). Before doing the t-test I had to transform my values because ...
0
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0answers
28 views

When do we have to standardize/normalize data?

I have to perform an independent group t-test and have unequal variances. From what I understand, the solution is to transform the data. To transform it, do I standardize it? Or simple use log10 to ...
0
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0answers
35 views

Which statistical test should I use to compare two samples?

I have two groups and must conduct hypothesis testing by using an appropriate stats test. Seeing as I have 26 participants in each group, do not have the standard deviation (or any other information ...
2
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1answer
32 views

Do I have to standardize my data to calculate variance?

I have 2 groups/samples. Correct me if I'm wrong, but before doing an independent-group t-test we have to verify the homogeneity of variance with Hartley's F-max test. When doing this test, we have ...
2
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1answer
41 views

Would multiple t-tests be appropriate

I have reaction time data from four different age groups, and I am hoping to prove that reaction time improves with age. I know that ANOVA would be preferred to determine if age has an effect, but I ...
2
votes
1answer
70 views

t test with log transformation

One of my variables to be compared in a t-test is normally distributed, while the other is non-normally distributed. What test should I use? I thought I should do a reflect log10 transformation on the ...
0
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1answer
15 views

Correction of mutliple paired samples t-test

In one group of subjects I have four parameters (for e.g. A, B, C, D) measured in two conditions. I want to know whether these 4 parameters differ between the conditions by doing paired samples ...
0
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0answers
20 views

T-test to check a significance

Is it okay to perform independent sample T-test to test the effect of an health awareness intervention on male and female population registered at 300 polling booths in a town.
2
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1answer
79 views
+50

Reporting degrees of freedom for Welch t-test

The Welch t-test for unequal variances (also known as Welch–Satterthwaite or Welch-Aspin) generally has a non-integer degrees of freedom. How should these degrees of freedom be quoted when reporting ...
0
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1answer
34 views

Difference between two measures

A numerical value was generated for each of 65 samples on machine A at time T, and then on machine B and time S. I tested for a difference between the two runs using R as follows: ...
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0answers
8 views

Balance checking in randomized controlled trials with large sample

I have a survey experiment in which the treated group receives a certain prompt that the control group does not. I also have a bunch of demographic variables that I want to check for balance between ...
0
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0answers
7 views

Compare model performance to distinguish two groups

I would like to compare a sample from the normal population NP to a sample from an "abnormal" population AP. I have several variables measured on both NP and AP, say age, gender, and VAR1, VAR2 and ...
0
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0answers
28 views

lay stats question

I am comparing two prospective observational cohorts; the "study group" (n=30) has undergone previous intervention that "failed" and has undergone a 2nd intervention. This is being compared with a ...
1
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0answers
16 views

Upper bound for sampling fraction for CLT to hold

What is the upper bound for the sampling fraction for the Central limit theorem to hold when sampling without replacement? Context The context for my question is that it is regularly argued (see e.g. ...
0
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0answers
64 views

White noise test interpretation

How to interpret white noise test from Stata? Have a white noise means that a variable does not have autocorrelation. Can I say here that all of my variables has a white noise (does not have ...
0
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1answer
44 views

Modeling within subjects

I am having a bit of a statistics problem, and thought I would throw it to the internet before I bash my head in. Participants were shown stimuli and asked a question while EEG was recorded. The ...
1
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2answers
63 views

Which test to use when t-test is not apropriate?

I have two groups, male and female teachers. I want to see if there is a statistically significant difference in mean pay. There are 48 male teachers, which is enough to use a t-test. However, there ...
0
votes
1answer
59 views

ANOVA or ANCOVA

I have to analyze a study where 2 treatments (t1 and t2) were used to control blood sugar levels. The 't2' is a new treatment which is being compared with an old established treatment 't1'. I have a ...
0
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0answers
17 views

T test as Mahalanobis distance

Our tutor once said that T test applies Mahalanobis distance (hope I've heard it right). Could you please explain, how it does so? Denis
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0answers
22 views

ARIMA, coefficients check

I would appreciate if someone could check the mathematical equation for the seasonal ARIMA (4,1,3) x (1,1,1) period 12 that I wrote. I have done it this way, but I am not really sure if it correct is. ...
0
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0answers
16 views

Compare two populations by their means… t-test?

I would like to have your opinion on the best way to compare two small sized populations of 13 and 14 individuals (but I have 3 tests for each individual on my dataset, so should I use 13 and 14 or 39 ...
0
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1answer
27 views

Compare means of two (contentwise) different variables

I have a question about comparing the means of two variables that have a different meaning but a (possibly) similar ways of measuring them. To give an example: Let's say I am conducting a study in ...
0
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0answers
12 views

Is this estimator for the standard error of a sample mean difference biased and what is the relation to Student's t-test?

In the situation of two indepdent samples, the variance of the difference in sample means $\bar{x}_1$ and $\bar{x}_2$ is $$Var(\bar{x}_d)=\frac{\sigma_1^2}{n_1}+\frac{\sigma_2^2}{n_2}=\sigma_d^2$$ and ...
6
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2answers
177 views

R t.test … NOT significant anymore

I got very confused while looking at help examples of the t.test function ...
2
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1answer
27 views

Paired difference test for nonhomogenous variances

Concrete scenario: A random sample of adults in Idaho rate each of 'kombucha', 'apple juice' and 'grape juice' on a scale from 0 to 1. Does the population of Idaho assign significantly different mean ...
1
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0answers
24 views

Significant difference within line set and between two sets of lines

For my research a person has walked on a treadmill which contains two pressure plates: One below the left foot, one below the right. I would like to compare the force in the z (downwards) direction ...
0
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2answers
31 views

Student's test for correlation coef

In one of the articles I found such a statement: The significance of the correlation coefficient was then verified using Student's t test for independent variables Is this incorrect or did I ...
0
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1answer
17 views

Can two samples of 189 and 50 undergo independent samples t test?

I have taken two types of subjects related to two categories one has a sample size of 189 and other has 50...Can I apply independent samples T test on them ????
0
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0answers
9 views

On computing the Wolfe's t-Test

I have a sample with $n=1000$ subjects. For each subject I have three variables measured, let's say $X$, $Y$ and $Z$. I have the following correlations: $r_{xz}$ = 0.80 $r_{yz}$ = 0.83 I want to ...
0
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1answer
33 views

Probabilistic comparison of two mixture models?

Given two gaussian mixture models (GMMs) with different degrees of freedom, is there a way to determine the probability that one is generated from the other? That is, can we give a probability to the ...
4
votes
1answer
48 views

When does an unpaired test result in higher p-value than a paired test?

I determined some parameter in a group of subjects under two conditions, such that each subject was tested in both conditions. I want to know if the condition has an effect on the parameter. My design ...
2
votes
1answer
49 views

Asymptotic distribution of a recursive statistic

I have a (time series related) test statistic which is asymptotically normal. I would like to know what is the asymptotic distribution of its maximal value obtained by a recursive estimation. For ...
0
votes
1answer
36 views

Statistical test of stock returns product

Say I have a sequence of stock returns: $X_1, ..., X_n$. Then I make a sample of products: $X_1X_2, X_2X_3, ..., X_iX_{i+1},..., X_{n-1}X_n$ How to test, if the sample mean is significantly different ...
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0answers
38 views

Advice on research study

I am collecting data on extroversion using a personality scale at a clinic. I have about 50 subjects where 15 are in experimental group receiving interventions. I am also collecting data on ...
1
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0answers
27 views

Using t-test for feature selection after z-scoring data?

Suppose I have a high-dimensional dataset, and a binary classification problem. I want to use the two-sample t-test for feature selection. If the data has been normalized by z-scoring (so it has zero ...